Your spleen is an organ located just below your rib cage on your left side. A number of conditions — from infections to liver disease and some cancers — can cause an enlarged spleen, also known as splenomegaly (spleh-no-MEG-uh-lee).

Most people don't have symptoms with an enlarged spleen. The problem is often discovered during a routine physical exam. Your doctor can't feel a normal-sized spleen in adults — unless you're very slender — but can feel an enlarged spleen. If you have an enlarged spleen, your doctor will likely request imaging and blood tests to help identify the cause.

Treatment for an enlarged spleen focuses on relieving the underlying condition. Surgically removing an enlarged spleen isn't usually the first treatment, but it may be recommended in certain situations.

An enlarged spleen may cause:

No symptoms in some cases

Pain or fullness in the left upper abdomen that may spread to the left shoulder

Feeling full without eating or after eating only a small amount — this can occur when an enlarged spleen presses on your stomach

Anemia

Fatigue

Frequent infections

Easy bleeding

When to see a doctor

See your doctor promptly if you have pain in your left upper abdomen, especially if it's severe or the pain gets worse when you take a deep breath.

A number of infections and diseases can contribute to an enlarged spleen. The effects on your spleen may be only temporary, depending on how well your treatment works. Contributing factors include:

Viral infections, such as mononucleosis

Bacterial infections, such as syphilis or an infection of your heart's inner lining (endocarditis)

Parasitic infections, such as malaria

Cirrhosis and other diseases affecting the liver

Various types of hemolytic anemia — a condition characterized by premature destruction of red blood cells

Blood cancers, such as leukemia, and lymphomas, such as Hodgkin's disease

Metabolic disorders, such as Gaucher's disease and Niemann-Pick disease

Pressure on the veins in the spleen or liver or a blood clot in these veins

How the spleen works

Your spleen is tucked under your rib cage next to your stomach on the left side of your abdomen. It's a soft, spongy organ that performs several critical jobs and can be easily damaged. Among other things, your spleen:

Filters out and destroys old and damaged blood cells

Plays a key role in preventing infection by producing white blood cells called lymphocytes and acting as a first line of defense against invading pathogens

Stores red blood cells and platelets, the cells that help your blood clot

An enlarged spleen affects each of these vital functions. For instance, as your spleen grows larger, it begins to filter normal red blood cells as well as abnormal ones, reducing the number of healthy cells in your bloodstream. It also traps too many platelets. Eventually, excess red blood cells and platelets can clog your spleen, interfering with its normal functioning. An enlarged spleen may even outgrow its own blood supply, which can damage or destroy sections of the organ.

Anyone can develop an enlarged spleen at any age, but certain groups are at higher risk, including:

Children and young adults with infections, such as mononucleosis

People who have Gaucher's disease, Niemann-Pick disease, and several other inherited metabolic disorders affecting the liver and spleen

People who live in or travel to areas where malaria is endemic

Potential complications of an enlarged spleen are:

Infection. Because an enlarged spleen can reduce the number of healthy red blood cells, platelets and white cells in your bloodstream, you may develop frequent infections. Anemia and increased bleeding also are possible.

Ruptured spleen. Even healthy spleens are soft and easily damaged, especially in car crashes. When your spleen is enlarged, the possibility of rupture is far greater. A ruptured spleen can cause life-threatening bleeding into your abdominal cavity.

An enlarged spleen is usually detected during a physical exam. Your doctor can often feel the enlargement by gently examining your left upper abdomen, just under your rib cage. However, in some people — especially those who are slender — a healthy, normal-sized spleen can sometimes be felt during an exam.

Your doctor may confirm the diagnosis of an enlarged spleen with one or more of these tests:

Blood tests, such as a complete blood count to check the number of red blood cells, white blood cells and platelets in your system

Ultrasound or computerized tomography (CT) scan to help determine the size of your spleen and whether it's crowding other organs

Imaging tests aren't always needed to diagnose an enlarged spleen. But if your doctor recommends imaging, you generally don't need any special preparation for an ultrasound or MRI. If you're having a CT scan, however, you may need to refrain from eating before the test. If you need to prepare, your doctor will let you know well in advance.

Finding the cause

Sometimes you may need further testing to identify what's causing an enlarged spleen, including liver function tests and a bone marrow exam, which can give more detailed information about your blood cells than can blood drawn from a vein.

In some cases, a sample of solid bone marrow is removed in a procedure called a bone marrow biopsy. Or you may have a bone marrow aspiration, which removes the liquid portion of your marrow. In many cases, both procedures are performed at the same time (bone marrow exam).

Both the liquid and solid bone marrow samples are frequently taken from the same place on the back of one of your hipbones. A needle is inserted into the bone through an incision. Because bone marrow tests cause discomfort, you'll receive either general or local anesthesia before the test.

Because of the risk of bleeding, a needle biopsy of the spleen is almost never done.

Occasionally, when there's no explanation for an enlarged spleen despite a thorough investigation for a cause, your doctor may recommend surgery to remove your spleen. After surgical removal, the spleen is examined under a microscope to check for possible lymphoma of the spleen.

If the cause of an enlarged spleen can be identified, treatment focuses on the underlying problem. For example, if you have a bacterial infection, treatment will include antibiotics.

If you have an enlarged spleen but don't have any symptoms and the cause can't be found, your doctor may suggest watchful waiting. You'll have to see your doctor for revaluation in six to 12 months, or sooner if you develop any symptoms.

If an enlarged spleen causes serious complications or the underlying problem can't be identified or treated, surgical removal of your spleen (splenectomy) may be an option. In fact, in chronic or critical cases, surgery may offer the best hope for recovery.

But elective spleen removal requires careful consideration. You can live an active life without a spleen, but you're more likely to contract serious or even life-threatening infections after having your spleen removed. Sometimes radiation can shrink your spleen so that you can avoid surgery.

Reducing infection risk after surgery

If you do have your spleen removed, certain steps can help reduce your risk of infection, including:

A series of vaccinations both before and after the splenectomy. These include the pneumococcal (Pneumovax 23), meningococcal and haemophilus influenzae type b (Hib) vaccines, which protect against pneumonia, meningitis, and infections of the blood, bones and joints. In addition, you'll need to get the pneumococcal vaccine every five years after surgery.

Taking penicillin or other antibiotics after your operation and anytime you or your doctor suspects the possibility of an infection.

Calling your doctor as soon as you know that you have a fever because this may indicate an infection.

Avoiding travel to parts of the world where certain diseases, such as malaria, are endemic.

If you have an enlarged spleen, avoid contact sports — such as soccer, football and hockey — and limit other activities as recommended by your doctor. Modifying your activities can reduce the risk of a ruptured spleen.

It's also important to wear a seat belt. If you're in an accident, a seat belt can help prevent injury to your spleen.

Finally, be sure to keep your vaccinations up to date because your risk of infection is increased. That means at least an annual flu shot, and a tetanus, diphtheria and pertussis booster every 10 years. Ask your doctor if you need any additional vaccines.

References

Landaw SA, et al. Approach to the adult patient with splenomegaly and other splenic disorders. http://www.uptodate.com/home. Accessed June 6, 2013.

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